I was wondering about this too.
I have 10 day hoppers booked with my package for August, but want to upgrade to an AP when I get there. I am the only one out of our group who wants to upgrade. I thought I heard something about only being able to do this at a park and that you could not do it at the resort. Does that sound right? And, if so, would I need to have my ticket separate from my room card?
Thanks for any help and adivce anyone may have.